Cut rear springs = still the same spring rate?
Thread Starter
Joined: Nov 2001
Posts: 45,353
Likes: 1,786
From: Chicago, IL
Cut rear springs = still the same spring rate? I know that Jay Billingsley told me the answer to the pros/cons of cutting stock rear springs but I for the life of me cannot remember his answer. 
Anyone?
I need to drop the rear of my car 2 inches. I want something that drops in. i have some cut rear springs I can try.
Anyone?
I need to drop the rear of my car 2 inches. I want something that drops in. i have some cut rear springs I can try.
Teching In
Joined: May 2004
Posts: 3
Likes: 0
From: Commerce Township, MI
Originally Posted by Pro Stock John
I know that Jay Billingsley told me the answer to the pros/cons of cutting stock rear springs but I for the life of me cannot remember his answer.
Anyone?
I need to drop the rear of my car 2 inches. I want something that drops in. i have some cut rear springs I can try.
Anyone?
I need to drop the rear of my car 2 inches. I want something that drops in. i have some cut rear springs I can try.
Even a small difference in overall spring height will seriously throw off your corner balance and induce axle hop.
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Accoding to Herb Adams "Chassis Engineering" trimming around 1/2 coil will increase the spring rate approximately 10%
In this same book Mr.Adams recommends trying to trim your stock springs (if their height and rate is near what you require) rather than buying new.
In this same book Mr.Adams recommends trying to trim your stock springs (if their height and rate is near what you require) rather than buying new.
2-3" high- yikes! You mentioned that this is an "early" housing. do you have any idea where the "late" ones sit in regards to ride height? My car is high looks high to me already and a really wanted to go 9", but I don't want a 4X4.
Thread Starter
Joined: Nov 2001
Posts: 45,353
Likes: 1,786
From: Chicago, IL
Silverghost has a newer 9" housing and does not have the same height problem as me.
I would like to have an increased spring rate and have them be stiffer. But they won't bottom out or do anything weird?
I would like to have an increased spring rate and have them be stiffer. But they won't bottom out or do anything weird?
Joined: May 2002
Posts: 3,299
Likes: 2
From: windsor, ont. canada - Home of the fastest LT1 6spd.
PSJ,
my car is a perfect example of what you want to do. i cut approximately 1 - 1.5 coils off of my rear springs, they are 1LE springs, so they are stiff to begin with. my car still leaves quite well.it has taken some time to figure out what adjustments to make, and there is still a bit of room for improvement, but we'll figure it out!
my car is a perfect example of what you want to do. i cut approximately 1 - 1.5 coils off of my rear springs, they are 1LE springs, so they are stiff to begin with. my car still leaves quite well.it has taken some time to figure out what adjustments to make, and there is still a bit of room for improvement, but we'll figure it out!
11 Second Club
Joined: Nov 2001
Posts: 411
Likes: 0
From: loretteville pq. MARS
Mine was lowered by 2 1/2"s back and front,absolutely NO weight transfer even with the Relo brackets.
That was 2 1/4 coils cut off in back and 2 in front.
My car is mild and only has 352 RWHP so if you have more power you will probably be able to get better launches.
My car was very boring of the line and I decided to do the front HALS[F] , Pro Star ,DS2's ,K&N filter,MSD wires,NGK plugs and Hyperteck coil and raise it back up by 1 1/2".
I though the diff would be about 1/10th or 2,,my best runs ever on this track in ideal conditins were 12.65s,,in crappy weather over the past 2 weeks I have run 12.43 -12.44-12.45 over the 2 weekends.
Had 2 baseline cars to compare to[no changes since last season]that both ran 1-2/10ths slower than last year.
TANER has tons of HP and is AMAZING,I love to see him launch because he has enough HP to offset the drop.
My OLD style[70 Mustang]9" raised the back about 3/4 of an inch when I installed it last year.
Noticed that I had to soften the HALS to 7 to take curves comfortably,any harder in front throws the rear out too easily,,,,will get HALS for rear next year!!!!
Good luck with your tests!!!!
That was 2 1/4 coils cut off in back and 2 in front.
My car is mild and only has 352 RWHP so if you have more power you will probably be able to get better launches.
My car was very boring of the line and I decided to do the front HALS[F] , Pro Star ,DS2's ,K&N filter,MSD wires,NGK plugs and Hyperteck coil and raise it back up by 1 1/2".
I though the diff would be about 1/10th or 2,,my best runs ever on this track in ideal conditins were 12.65s,,in crappy weather over the past 2 weeks I have run 12.43 -12.44-12.45 over the 2 weekends.
Had 2 baseline cars to compare to[no changes since last season]that both ran 1-2/10ths slower than last year.
TANER has tons of HP and is AMAZING,I love to see him launch because he has enough HP to offset the drop.
My OLD style[70 Mustang]9" raised the back about 3/4 of an inch when I installed it last year.
Noticed that I had to soften the HALS to 7 to take curves comfortably,any harder in front throws the rear out too easily,,,,will get HALS for rear next year!!!!
Good luck with your tests!!!!
TECH Enthusiast
Joined: Oct 2002
Posts: 593
Likes: 0
From: Chicago
Originally Posted by 01-Z
Tell me about them.
How much?
What does it take to put them in?(welding,ect)
Any pics?
How much?
What does it take to put them in?(welding,ect)
Any pics?
They bolt up as stock replacement where your shocks are. I'll see if I can get you some pics. My car is over at Hoger's again and then to FLP to check the trans before NvsS
I think they were about $550.
Sorry I'm so late to this thread, but here is your answer Jon.
It definitely increases the spring rate. Same weight of car is on the springs, only now there will be fewer coils to absorb the weight.
Think of it this way, a coil spring is really a torsion bar wound in a helix. What happens to a torsion bar when you shorten it, it gets stiffer.
Hope it helps, if you need/want exact rate change or rate, let me know, I can calculate it for you.
It definitely increases the spring rate. Same weight of car is on the springs, only now there will be fewer coils to absorb the weight.
Think of it this way, a coil spring is really a torsion bar wound in a helix. What happens to a torsion bar when you shorten it, it gets stiffer.
Hope it helps, if you need/want exact rate change or rate, let me know, I can calculate it for you.
I'll be messing with mine this week,I'm gonna start at one coil off each side..I dont like the gap I have either and it does help tighten up the sups. from what I gather too.